Precise phase control of light sources in microscope instruments is important for various optical techniques that involve interference of separate beams as well as polarization optics. For instance, phase control is used in phase contrast microscopy, differential interference microscopy, and polarized light microscopy. In particular, precise and fast phase control is used in structured illumination microscopy, in which phase control of interfering beams is accomplished with precise changes in path lengths of separate beam paths on the order of fractions of a wavelength, which for visible light corresponds to a change in the path length of 10 nanometers or less. Typically, a piezo-electric translation device with a mounted mirror can be used to generate precise phase control. As the mirror is translated parallel to the beam path, the path of the beam is lengthened or shortened by approximately 2 times the minor travel distance. Although the position of the mirror can be changed on order of 1-2 milliseconds, the devices are expensive and generate a detectable amount of beam translation except for a 0° angle of incidence. An alternative approach is to use an electronically deformable window to modulate the phase. A voltage applied to the window changes the thickness of the window by fractions of a wavelength, which results in a change in the effective path length of the light transmitted through the window. Unlike the piezo-electric device, the deformable window transmits the beam without beam translation. However, deformable windows are considerably slower with switching times on the order of tens to hundreds of milliseconds and it is difficult to achieve extremely low optical distortion, because the window is undergoing physical deformation. For the above described reasons, engineers, scientists, and microscope manufacturers continue to seek faster systems and methods for changing the phase in the light used to illuminate a specimen.